A related push-type data delivery service in which servers in networks automatically transmits data to mobile terminal devices is known.
With a server that provides such a push-type data delivery service, if, for example, a calendar or an address book stored in the server is updated, the server automatically transmits, to a mobile terminal device, data used to synchronize the calendar or the address book stored in the mobile terminal device. In such a case, the mobile terminal device passively receives the data transmitted by the server and, by using the received information, updates the calendar or the address book stored in the mobile terminal device.
Furthermore, if the server that provides the push-type data delivery service acquires, for example, an email to be sent to a mobile terminal device, the server transmits the acquired email to the mobile terminal device. In such a case, the mobile terminal device receives the email transmitted from the server and displays the received email.
At this time, if the mobile terminal device transmits and receives data via a 3rd generation mobile telecommunications (3G) network, the mobile terminal device receives its allocated Internet Protocol version 4 (IPv4) address from the server in the 3G network. Furthermore, if the mobile terminal device does not synchronize again with the server in the 3G network within a predetermined time period after the allocated IPv4 address is received, the allocation of the IPv4 address is released in order to prevent IPv4 address exhaustion.
However, if the allocation of the IPv4 address is released, the mobile terminal device does not transmit and receive data via the 3G network; therefore, it is not possible for the mobile terminal device to receive a push-type data delivery service. This is the reason the mobile terminal device has an Always-On function that synchronizes with a server in the 3G network at predetermined time intervals.
Specifically, a mobile terminal device that has an Always-On function synchronizes with the server in the 3G network at predetermined time intervals, and thereby the mobile terminal device retains the allocation of the IPv4 address. Then, the mobile terminal device receives data or an email that is automatically transmitted from the server in the network and then performs various processes.    Patent Document 1: Japanese Laid-open Patent Publication No. 2006-310983    Patent Document 2: Japanese Laid-open Patent Publication No. 2003-134566
However, with the mobile terminal device described above that has the Always-On function, because the mobile terminal device always receives data or an email transmitted from a server that provides the push-type data delivery service, there is a problem in that the amount of electrical power consumed the mobile terminal device increases.
For example, even if the mobile terminal device is in a standby state, the mobile terminal device still synchronizes with the server in the 3G network at a predetermined time intervals in order to retain the allocated IPv4 address; therefore, the amount of electrical power consumption increases. Furthermore, for example, even if the mobile terminal device is in a standby state, the mobile terminal device receives data or an email that is automatically transmitted from a server that provides the push-type data delivery service; therefore, the amount of electrical power consumption increases.
In the following, the amount of electrical power consumed by a mobile terminal device will be described. FIG. 26 is a schematic diagram illustrating an example of the Always-ON function performed by a mobile terminal device. Furthermore, FIG. 26 illustrates an example of a graph indicating the amount of the current that flows in a mobile terminal device that has an Always-On function. Furthermore, in FIG. 26, the vertical axis indicates the amount of the current [mA] flowing in a mobile terminal device, and the horizontal axis indicates the time [Second (Sec)]. Furthermore, in the example illustrated in FIG. 26, it is assumed that the mobile terminal device synchronizes with a server in a network at 28-minute intervals by using the Always-On function.
As illustrated at (h) in FIG. 26, the mobile terminal device performs synchronization with the server in the 3G network using the Always-On function. Furthermore, as illustrated by the arrow (i) in FIG. 26, if the mobile terminal device does not synchronize with the server in the 3G network within the time period of 28 minutes elapsing, the mobile terminal device synchronizes again with the server in the 3G network, as illustrated at (j) in FIG. 26.
FIG. 27 is a schematic diagram illustrating an example of the amount of electrical power consumed when a mobile terminal device synchronizes with a server in a 3G network. In the example illustrated in FIG. 27, similarly to the example illustrated in FIG. 26, the vertical axis indicates the amount of the current [mA] flowing in the mobile terminal device, and the horizontal axis indicates the time [Sec]. For example, in the example illustrated in FIG. 27, the mobile terminal device synchronizes with the server in the 3G network after 10 seconds have elapsed since the time measurement started. An average of 222.24 [mA] flows in the mobile terminal device for 10.63 seconds.
At this time, if the Always-On function is performed, the average current flowing in the mobile terminal device becomes 5.29 [mA]. In contrast, if the Always-On function is not performed, the average current flowing in the mobile terminal device becomes 3.28 [mA]. In this way, if the mobile terminal device performs the Always-On function, the electrical power consumption increases.
In the following, a description will be given of a case in which, electrical power consumption increases due to the mobile terminal device passively receiving an email or data when the mobile terminal device is in a standby state. FIG. 28 is a schematic diagram illustrating an example of the amount of electrical power consumed when a mobile terminal device is in a standby state. In the example illustrated in FIG. 28, the vertical axis indicates the amount of current [mA] flowing in the mobile terminal device when it is in the standby state, and the horizontal axis indicates the time [Sec].
In the example illustrated in FIG. 28, as illustrated by the arrow (k) in FIG. 28, because the mobile terminal device has not synchronized with the server in the 3G network for 27.2 minutes, the mobile terminal device automatically synchronizes with the server in the 3G network by using the Always-On function. Furthermore, in the example illustrated in FIG. 28, the mobile terminal device receives, using the push-type data delivery service, data that is used to perform synchronization of calendars that is performed at the time indicated by (l) and (m) in FIG. 28 and receives an email at the time indicated by (n). Specifically, because, in addition to the electrical power consumption due to the Always-On function, the mobile terminal device also consumes electrical power when it receives data related to the push-type data delivery service when the mobile terminal device is in a standby state; therefore, the electrical power consumption increases.
According to an aspect of the present invention, the technology disclosed in the present invention reduces the electrical power consumed by a mobile terminal device.